Clamping device



Aug. 28, 1928. 1,682,314

R. E. wALToN CLAMPING DEVICE FOR VALVE SEAT BEAMER PILOTS Filed OCl'.. 5l, 1927 Figi.

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Patented Aug. 28, 1928.A

ROBERT E. WALTON, OF TAGOHA, WASHINGTON. 4

CLAHPING DEVICE FOB VALVE-SEAT-REAMER PILOTS.

'Apliicmn med october si, 1927. serial No. 229,951.

This invention relates to tools for regrinding the valve-seats of gasoline engines, and for other similar purposes, and especially to the means for centering' and clamping the 5 pilot for such a tool. The object of my invention is to firmly clamp the pilot for the grinding tool'in exact coaxial alinement with the axis of the valve-stem-guide. Other ob- ]ects are to provide such a device, first, which l0 is inserted complete in the valve-stem-guide from the valve end thereof; second, which is tightened and clamped entirely by the rotation of the valve end of the pilotitself third,

'which will clamp the pilot in such axial position independent of the wear of the valvestem-guide bushing fourth, which is provided with a clamping means interposed between the pilot stein and the valve-stemg'uide bushin fifth, which grips the valvestem-guide ushing yat three separated places; sixth, which grips thepilot stem at two'separated places; seventh, in which the several clampingmeans are independent but are interacting, whereby the rotation of the pilot acts to tighten all the clam s equally; and eighth, which is cheap-to ma e, easy to apply,` and which effective y holds the pilot, with great firmness, in a position coaxial with the valve-stem-guide.

I attain these and other objects by the devices, mechanisms, and arrangements villustrated in the accompanying drawings, in which Fig. 1 is a vertical section showing my improved device in use in a valve-stem-guide which has been badly worn by use; Fig. 2 is an elevation of the pilot' Fi s. 3 and 4 are plan and elevation, respedtive y, of the upper clamp bushing; Fig. 5 is a vplan of the lower end of said up er clainip bushing and of the upper end of t e clamping nut; Fig. 6 is an elevation of the clamping nut: Figs. 7 and 8 are plan and elevation, respectively, of the loose wedge sleeve.

Similar numerals of reference refer to similar parts throughout the several views.

In my application for patent for valve seat reamer pilot, filed on July 1st, 1927, under Serial Number 202,824, I secure the pilot stem to the valve-stem-guide by passing the stem through the hole 1n the (guide, centering its upper end on the gui e, and afterwards screwin a centering and clamping nut on its lower en engaging the lowerend of the uide. However, it often happens that it is inconvenient to have to apply the nut to the p ilot from below the valve stem guide, especially if the springs or other devices have to be removed, and I have therefore devised the following described clam ing means which is assem led complete beibre being inserted in the valve-stem-guide, and which is tightened entirely by the rotation of the pilot itself, after ithas been thus inserted in place, and which is loosened by the corresponding reversed rotation and does not require the application of heavy force to remove it therefrom, as is the case when the pilot is tapered and is driven into place.

When it has become necessary to require the valve-seat of a gasoline engine to be recut or ground, it is' usually true that the valve-stem-guide bushing has become considerably worn and the hole unequally enlarged, especiall at its two ends. Devices have been produce which comprise a loose split busliing, with tapered inner surface, and a correspondingly tapered stem for the pilot, the bushing being first inserted in the valvestem-guide and then the pilot stem being driven thereinto, but it will be observed that as soon as any point of the bushing clamps in the valve-stem-guide hole, it is impossible to Vdrive the pilot any further and therefore,

'when the hole is worn larger at the ends, the said bushing will grip the center of the hole only and the pilot willwobble when grinding force is applied thereto. To overcome this objection Iv have divided the clamping device into two bushings which are independently expanded to grip the guide hole in three different points and which grip the pilot stemat the two ends, which said bushings are operated by screwing the pilot in a nut, formed integral with one said bushing, and which slide longitudinally on the stem, as it is turned, until all the bushings grip the hole with equal force at the three oints of contact, the ends of the compound device expanding to gripthe wornfends of the hole while the centra part expands onl to grip the comparatively unworn center t ereof.

vReferring to the drawings, the valve cage 'l is provided with the usual valve-seat 2, and the valve-steni-guide 3 is formed integral therewith and may therein. The hole 4 of the guide 3 vis forme originally-with cylindrical sides but is shown in Fig. 1 as considerably worn so that its two ends are of larger diameter than the central part thereof. i

The pilot comprises a main cylindrical have a lining or bushing p surface. The degree of these tapers is preferably the same as that of the shoulder 7 of the pilot.

The upper clamp bushing (Figs. 3, 4 and 5) comprises a. cylindrical part 12, titting loosely in the hole 4 of the valve-stem-guide, and provided with a shoulder or collar 13 extending around its upper end. The parts 12 and 13 are split by three slots 14 extending downward from the up r end towards the lower end thereof, and t e part 12 is also provided with three other slots 15 (out of'alinement with the slots 14) extending upward from the lower Yend thereof. The upper and the lower ends of the said bushing may be independently Aexpanded therefore. An axial hole 16 passes through the bushing and is of such diameter as to permit the bushin to slide free- .ly on-the stem 6 of the pilot. `he upper and the lower ends of said hole 16 are tapered outward'to t on the corres ondingly tapered shoulder 7 of the pilot and) on the upper tapered end 10 of the sliding sleeve 9, respectively.

The clamping nut (Figs. 5 and 6) com prises a. cylinder 17 with a central hole 18, screw-threaded at its lower end to lit the threads 8 of the pilot stem 6. The upper part of this cylinder 17 is split with three slots 19 extending downward towards its lower end. I prefer to slightly expand this upper end of the cylinder 17 in order that the cylinder ma readlly enter the guide hole 4 and yet will en age the said hole with suilicient friction to hold 1t from turning when the ilot is turned to be screwed down 1n the nut 1 The upper part of the central hole 18 is tapered outward to corres ond with the lower tapered end-11 of the sli g sleeve 9.

The pilot shank 5 is provided with a hole 20 adapted to receive a suit-able pin whereby it may be turned when it is desiredjto tighten or loosen the clamps.

The cutting tool 21is mounted on the ta.- pered end 22 of the turning shank 23, which 'ts snugl on the pilot shank 5, and is free to be turne and to slide axially thereon.

My invention is assembled, iirst, by slipping the upper bushing 12 and the sliding sleeve 9 on t e stem 6, and then by screwing the nut 17 thereon; but the said nut 17 should not be screwed up thereon suciently to bring the corresponding tapered surfaces into forcible contact with each other. When my invention is to be used the pilot, with the parte thus assembled thereon, is inserted in the hole 4 of the valve-stem-guideB as far as possible,

then the pilot is turned by means of a pin in the hole 20 therein. The nut 17 comes in frictional contact with the wall of the hole 4 and therefore the stem 6 is drawn downward, or the nut 17 is drawn upward, as the pilot is thus turned. The tapered shoulder 7 is thus dawn down into the upper corresponding tapered portion of the upper bushing 12, and the bushing 12 is forced down on to the sleeve 9, and the sleeve 9 is forced down into the -upper end of the nut 17. As soon as all `three correspondingly tapered parts 7, 10-and 11 are in contact with the complementary parts of the bushing 12 and the nut 17, then further rotation of the stem 6 draws the t-wo parts 7 and 17 towards each other and therefore slides the shoulder 7 or one or both of the tapered ends 10 and 11 in the saidcomplementary parts and correspondingly expands the diameters of the parts 12 and 17 at the three points. As soon as it has been expanded at one said point to come in tight contact with the wall of the hole 4 at that point, then further rotation of the stem 6 ceases to expand that point and is ei'ective in expanding the other two points of expansion. For instance, if the central point has first come into contact with the wall of the hole, then the bushing 12 and the sleeve 9 remain stationary while the shoulder 7 is drawn down to expand the upper part of the bushing 12 and the nut 17 is correspondingl drawn upward on the tapered end 11 ofy the sleeve 9 to expand its upper end. Or, if it is the upper part of the bushing 12 which has lirst been expanded into contact with the wall of the hole V4, then the shoulder 7 and bushing 12 do not move axially and both the nut 17 and the sleeve 9 move upward, thus expanding the up er endr of the nut 17 and the lower end of t e bushing 12. Thus it will be seen' that the stern 6 may be rotated to tighten the clamps as long as any one of the three expanding parts has not reached its gr'pping contact and until all are in equal clamping strain.

Also, it is evident that the contact between the shoulder'7 and the bushing 12 centers the stem 6 in the axis of the upper part of the hole 4, while the nut 17 is centered in the lower partthereof by the expansion of its u per part; and that as soon as the stem 6 has een screwed tightly in the nut 17 the said nut will center the stem in the lower part of the hole 4. The stem 6 and the pilot are therefor centered in the axis of the valve-stem-guide hole.

Also, it is evident that the lon itudinal strain applied to the stem 6, in tight y screwing it in the said nut 17 firmly clamps the stem' and the pilot in such axial position.

Having, therefore, described my invention, what I claim is 1. A clamping device for valve-seat reamer pilot comprising a pilot having a cylindrical upper portion and a reduced screw-threaded stem Awith a tapered Shoulder joining the 'lou said upper part to the said stem; an expanding bushing in contact with said shoulder and lying in the valve-stem-guide; a nut on the stem and engaging the valve-stem-guide to draw the said shoulder into the bushing to expand the bushing at the shoulder, whereby the top of the stem is centered in the valvestem-guide and the pilot is clam ed therein; and expanding means engaging t e lower end of the valve-stemguide whereby the lower end of said stem is centered therein.

2. A clamping device for valve-seat reamer pilot comprising a pilot having a cylindrical upper portion and a reduced screw-threaded stem; with a tapered shoulder joining the said upper part to the said stem; an expanding bushin in contact with said shoulder and lying 1n the valve-stcm-guide; a nut on the stem and en agin the valve-stemuide to draw the sai shou der into the bushmg to ex and the bushing at the shoulder, whereby t e toof the stem is centered in the valve-stemgui e and the pilot is clamped therein; expanding means engaging the lower end of the valve-stemuide whereby the lower end of said stem 1s centered therein; and intermediate strain-transmitting means whereby both said expanding parts are equally strained by the screwing of the stem in the nut.

3. A clamping device for valve-seat reamer pilot comprlsing a pilot having a cylindrical i upper portion and a reduced screw-threaded stem; with a tapered vshoulder joining the said upper part to the said stem; a bushing lying in the valve-stem-guide and loosely mounted on said stem and split at its ends,

whereby each end may be independently ex- 4. A clamping device for valve-seat reamer pilot comprising a pilot having a cylindrical upper portion and a reduced screw-threaded stem; with a tapered shoulder joining the said upper part to the said stem; a bushing lying 1n the valve-stein-guide and loosely mounted on said stem and s lit at its ends, whereby each end may be in ependently expanded, one end of said bushing adapted to contact with said tapered Shoulder to be exsaid stem below said bushin and having its upper and lower ends tapere the upper said tapered end being adapted to contact with the lower end of saidbushing to vexpand it; and a cylindrical nut, screw-threaded at its lower end and split at its upper end whereby' it ma beexpanded, said u per end bein enga by the lower tapere end of said s eeve to expand it, whereby when the ilot and stem are rotated both endsv of sai bushing and the upper end of said nut are all independently expanded into contact with the several parts of the valve-stem-guide to center the stem therein.

' ROBERT E. WALTON.

lpanded thereby; a sleeve loosely mounted on 

